Plasmonic Imaging of Electrochemical Reactions at Individual Prussian Blue Nanoparticles.

Adaly Garcia,Shaopeng Wang,Kinsley Wang,Yixian Wang,Fatima Bedier,Zijian Wan,Miriam Benavides

doi:10.3389/fchem.2021.718666

Abstract

Prussian blue is an iron-cyanide-based pigment steadily becoming a widely used electrochemical sensor in detecting hydrogen peroxide at low concentration levels. Prussian blue nanoparticles (PBNPs) have been extensively studied using traditional ensemble methods, which only provide averaged information. Investigating PBNPs at a single entity level is paramount for correlating the electrochemical activities to particle structures and will shed light on the major factors governing the catalyst activity of these nanoparticles. Here we report on using plasmonic electrochemical microscopy (PEM) to study the electrochemistry of PBNPs at the individual nanoparticle level. First, two types of PBNPs were synthesized; type I synthesized with double precursors method and type II synthesized with polyvinylpyrrolidone (PVP) assisted single precursor method. Second, both PBNPs types were compared on their electrochemical reduction to form Prussian white, and the effect from the different particle structures was investigated. Type I PBNPs provided better PEM sensitivity and were used to study the catalytic reduction of hydrogen peroxide. Progressively decreasing plasmonic signals with respect to increasing hydrogen peroxide concentration were observed, demonstrating the capability of sensing hydrogen peroxide at a single nanoparticle level utilizing this optical imaging technique.

Highlights

Prussian blue, first discovered as a pigment, is composed primarily of a ferrous ion connected to a ferric ion via a cyanide bridge, allowing for efficient electron transfer (Kong et al, 2015; Hegner et al, 2016)
Non-contact air-mode atomic force microscopy (AFM) was used to assess the size and geometry of the prepared Prussian blue nanoparticles (PBNPs) adhered to a gold sensing chip, and Figures 2A–D show that both types have wide distributions in size
By synthesizing two types of Prussian blue nanoparticles, type I and type II, we examined and compared their structures and electrochemical activities using AFM and plasmonic electrochemical microscopy (PEM)

Summary

Introduction

First discovered as a pigment, is composed primarily of a ferrous ion connected to a ferric ion via a cyanide bridge, allowing for efficient electron transfer (Kong et al, 2015; Hegner et al, 2016). As a result of its physical features and electronic richness (Fang et al, 2016), over the past few decades, this pigment has been used for energy storage and conversion (Jiménez-Gallegos et al, 2010; Chen et al, 2016), sensing (Karyakin et al, 1995), drug delivery (Wang et al, 2013), and catalysis (Sitnikova et al, 2014; Xuan et al, 2017; Ma et al, 2019). Sensing small amounts of hydrogen peroxide gives many insights about cells’ status and levels of oxidative stress and inflammation (Karyakin et al, 2004; Mao et al, 2011; Komkova et al, 2013)

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Results

Conclusion